Nanoshell therapy

ABSTRACT

Nano-constructs comprising nanoshells and methods of using the nano-constructs for treating or ameliorating a vascular condition are provided.

FIELD OF THE INVENTION

This invention is generally related to using nanoshells for treating orameliorating a vascular condition such as atherosclerotic plaque.

DESCRIPTION OF THE STATE OF THE ART

Stents are used not only as a mechanical intervention of vascularconditions but also as a vehicle for providing biological therapy. As amechanical intervention, stents act as scaffoldings, functioning tophysically hold open and, if desired, to expand the wall of thepassageway. Typically, stents are capable of being compressed, so thatthey can be inserted through small vessels via catheters, and thenexpanded to a larger diameter once they are at the desired location.Examples in patent literature disclosing stents which have been appliedin PTCA procedures include stents illustrated in U.S. Pat. No. 4,733,665issued to Palmaz, U.S. Pat. No. 4,800,882 issued to Gianturco, and U.S.Pat. No. 4,886,062 issued to Wiktor.

One strategy of biological therapy can be achieved by medicating thestents. Medicated stents provide for the local administration of atherapeutic substance at the diseased site. However, in many patients,especially diabetic patients, stentable lesions are focal manifestationsof widespread vascular disease. The advent of drug eluting stents hasbrought relief from restenosis of the treated lesion, but leavesprogression of regional vascular disease unaddressed. Moreover, drugrelated therapies sometimes can lead to undesirable side effects.

The embodiments described below address the above-identified problems.

SUMMARY

The present invention provides methods for treating or amelioratingvascular conditions using nano-constructs that include nanoshells. Thenanoconstructs can be delivered to a target tissue such as a diseasedtissue in a subject by any mode of delivery, e.g., injection. Upondelivery, the nano-constructs can reach the target site via passivetargeting or active targeting. Energy can then be applied to thenano-constructs. Upon exposure to energy, the nano-constructs can absorbthe energy and translate the energy into heat, thereby ablating thediseased tissue.

In some embodiments, it is provided a method of treating or amelioratinga vascular condition, the method including:

(a) administering to a subject nano-constructs capable of absorbingenergy from an electromagnetic radiation or energy from a fluctuatingelectromagnetic field and translating the energy into heat,

(b) causing the nano-constructs to reach a target tissue, and

(c) applying an energy to the nano-constructs to cause thenano-constructs to heat the target tissue,

wherein the nano-construct comprises a nanoshell.

In some embodiments, it is provided a medical device for treating orameliorating a vascular condition, the device including:

(a) nano-constructs that comprises nanoshells, and

(b) delivery means for delivering the nano-construct to a target tissueof a subject,

wherein the nanoshells are capable of absorbing an energy from anelectromagnetic radiation or energy from a fluctuating electromagneticfield and translating the energy into heat.

Examples of the vascular condition that can be treated or ameliorated bythe method described herein include, but are not limited to,atherosclerotic plaque.

DETAILED DESCRIPTION

The present invention provides nano-constructs for treating orameliorating a vascular condition. The nano-constructs includenanoshells capable of capable of absorbing energy from anelectromagnetic radiation or energy from a fluctuating electromagneticfield and translating the energy into heat.

The nano-constructs described herein have nanoshells formed on a corematerial. The nanoshells include a metal, carbon, or a conductingpolymer. The nano-constructs can be administered to a target tissue of asubject, which can be human or an animal. An energy source can then beapplied to the nano-constructs. The nano-constructs absorb the energyand then translate the energy into heat, thereby providing therapy tothe subject.

The nano-constructs can be used to treat or to ameliorate a vascularcondition such as atherosclerotic plaque. Other vascular conditions thatcan be treated or ameliorated the vascular condition include, but arenot limited to, vulnerable plaque, vascular inflammation, diffuseatherosclerotic disease, or restenosis.

In some embodiments, the nanoshells include a metal or an alloy. Usefulmetals include gold or gold alloy. In some embodiments, the metal ormetal alloy can include silver, platinum, palladium, chromium, iridium,biodegradable metals such as magnesium, zinc, calcium, or tungsten, oralloys thereof.

In some embodiments, the nanoshells include carbon. In some embodiments,the nanoshells can have a conducting polymer. Conducting polymers canbe, for example, poly(pyrrole), poly(thiophene), poly(acetylene),poly(aniline), graphite, carbon nanotubes, DNA or combinations thereof.

The nanoshells have a thickness in the range between about 2 nm andabout 100 nm. Thickness of the shells and the ratio of core to shelldimension is relevant to the frequency of electromagnetic radiation orirradiation that the shells can absorb and translate into heat. Forexample, for nanoshells formed of a metal such as gold, the wavelengthat which extinction efficiency is maximal shifts to longer wavelength ascore to shell ratio increases, i.e. as shell thickness decreases if theouter diameter is kept constant. Most relevant, the nanoshells can bedesigned such that they absorb radiation energy in the near-infraredspectrum between 650nm and 900nm which is permeable for tissue (see,e.g., Oldeburg S. J., et al., Applied Physics Letters; Vol. 75(19):2897-2899; Oldenburg S. J., et al., Chemical Physics Letters 288:243-247(1998)).

The nanoshells can be formed on a non-conducting core material that caninclude, for example, silicon oxide, silica, aluminum oxide,biopolymers, a polymer, or a combination of these.

The nano-constructs described herein can be delivered to a subject fortreating or ameliorating a vascular condition such as atheroscleroticplaque. Upon delivery, the nano-constructs can reach the target site viapassive targeting or active targeting. Passive targeting can be achievedby extravasation of the nano-construct through leaky vasculature such asthose present in atherosclerotic plaque. In some embodiments, the resultof passive targeting can be assessed by the time span after delivery ofthe nano-constructs and the circulation time of the nano-constructsafter delivery. Generally, the longer the nano-constructs remain incirculation, the more the nano-constructs can reach the target site ortarget tissue, which sometimes is also referred to as the diseased siteor diseased tissue. Therefore, in some embodiments, passive targetingcan be enhanced by increasing circulation times by rendering the surfaceof the nano-construct stealthy using a compound such as poly(ethyleneglycol). Other compounds that can be used to stealth the nano-constructsinclude, but are not limited to, hyaluronic acid, phosphoryl choline,dextran, dextrose, sulfo betaine, polypyrrolidone, poly(2-hydroxyethylmethacrylate), albumin, poly(acrylic acid), and poly(methacrylic acid)and PVA.

Extravasation of the nano-constructs is also related to the position andnature of the diseased tissue. The capillary walls of tumor vasculatureand the inflamed vasculature of diseased tissue is leaky compared tonormal tissue. In some embodiments, extravasation can be achieved bycirculation of the nano-constructs in the blood stream for a periodranging from 10 minutes to 120 hours, more specifically ranging fromabout 4 hours to 48 hours.

In some embodiments, the targeting can be achieved by active targeting.Active targeting can be carried out by attaching a targeting molecule onthe nano-constructs (e.g., nanoshells). Targeting molecules include anypeptide, antibody, or polysaccharide that has affinity to the targettissue or target site (e.g., atherosclerotic plaque). In someembodiments, the targeting molecule can be a surface-conjugated ligandagainst a receptor on an inflamed endothelium. Some examples of thetargeting molecules are antibodies to CD34, RGD, YIGSR, peptides andantibodies to IIbIIIa, heparin, hyaluronic acid, laminin, collagen,ICAM-1, ICAM-2, ICAM-3, fibrinogen, fibronectin, vitronectin,thrombospondin, osteopontin, integrins, VCAM-1, N-CAM, PECAM-1, IgCAM,folate, oligonucleotide aptamers, selectins, and cadherins.

The result of active targeting can be assessed by measuring the quantityof nano-constructs in the targeted tissue (i.e. vessel wall) versus thequantity administered. Similar to passive targeting, in someembodiments, the result of active targeting can be assessed by the timespan after delivery of the nano-constructs and the circulation time ofthe nano-constructs after delivery. Generally, the longer thenano-constructs remain in circulation, the more the nano-constructs canreach the target site. Therefore, in some embodiments, active targetingmediated by a targeting moiety can be enhanced by increasing circulationtimes by stealthing the surface of the nano-construct using a compoundsuch as poly(ethylene glycol). Other compounds that can be used tostealth the nano-constructs include, but are not limited to, hyaluronicacid, phosphoryl choline, dextran, dextrose, sulfo betaine, poly(vinylalcohol) (PVOH), polypyrrolidone, poly(2-hydroxyethyl methacrylate),albumin, poly(acrylic acid), and poly(methacrylic acid) and PVA.

Active targeting of the nano-constructs is also related to the positionand nature of the diseased tissue. Nano-constructs can reach diseasedtissue, which is highly vascularized, by systemic administration.Diseased tissue protected by the blood-brain barrier, which can preventpenetration of the nano-constructs, could be more advantageouslyaccessed by administration into cerebro-spinal fluid. If a highconcentration of nano-constructs is desired in the vessel wall of aportion of the vascular system, then administration by local deliverycatheter may be employed. Some target tissues such as the eye orprostate can be accessed externally by direct injection. In someembodiments, active targeting can be achieved by circulation of thenano-constructs in the blood stream for a period ranging from 10 minutesto 120 hours, more specifically ranging from about 4 hours to 48 hours.

Methods of Forming Nanoshells

Nanoshells can be formed on a core material using established methods.For example, U.S. Pat. No. 6,699,724 describes forming conductingnanoshells on a non-conducting core. The size and thickness of thecore/shell can be tuned so that the particles can absorb light with adesired wavelength. Biomolecules such as proteins or peptides can beattached to the nanoshells for binding to a specific tissue.

U.S. Pat. No. 6,685,986 describes a method of forming metal nanoshellsupon a core substrate. The nanoshells can be formed of a metal such asgold or a conducting polymer. The core substrate can be particles ofsilicon dioxide, titanium dioxide, alumina, zirconia, poly(methylmethacrylate) (PMMA), polystyrene, gold sulfide, macromolecules such asdendrimers, semiconductors such as CdSe, CdS, or GaAs. The particles canfurther have polyvinyl alcohol (PVA), latex, nylon, Teflon, acrylic,Kevlar, epoxy, or glasses. Some other references, for example, U.S.application publication Nos. 2003/0164064, 2002/0061363, 2002/0187347,2002/0132045, and 2005/0056118, also describes various methods offorming metal nanoshells on a core substrate. Formation of partialnanoshells can be formed according to the method described in, forexample, U.S. Pat. No. 6,660,381.

In some embodiments, the nanoshells can be formed via metal colloidalnanoparticles such as colloidal gold nanoparticles. For example,colloidal gold nanoparticles of 3-4 nm size can assemble on nanoparticlesurfaces functionalized by amine groups. These nanoparticles act asnucleation sites, and when a gold salt is present in a reducingenvironment, a solid gold shell can be formed around a nanosize templatesuch as a nanosphere.

In some embodiments, polymeric nanoparticles such as commerciallyavailable polystyrene particles modified at their surface to presentamine groups may be used as a template for gold nanoshells. Aminefunctionality can be placed onto these polymers by a variety oftechniques. For example, polymeric surface can be modified to have aminefunctionality via plasma treatment in the presence of ammonia orhydrazine. This plasma process can be carried out on preformednanoparticles by agitating them in a plasma reactor. Amino groups canalso be incorporated into the end-groups of a polymer (e.g., abiodegradable polymer), if the initiator contains both a hydroxyl groupand an amino group protected by a carbobenzoxy group or at-butoxycarbonyl group, and this initiator is used to make abiodegradable polymer by ring opening polymerization, such aspoly(L-lactide) or polyglycolide. After the polymerization, theprotecting group can be removed, liberating the amino group. Polymericmethacrylates can be made with amino groups by using a monomer such asN-(3-aminopropyl)methacrylamide. A copolymer with other monomers suchhas butyl methacrylate or methyl methacrylate can be made. In someembodiments, a dispersion or emulsion polymerization process can be usedto form monodisperse nanoparticles with surface amino groups (see, e.g.,Ramos; Jose, Forcada; Jacqueline Polymer 47(4):1405 (2006); Ramos; Jose,Forcada; Jacqueline, Polymer Chemistry 43 (17):3878 (2005); Prakash, G.K. et al., J. of Nanoscience and Nanotechnology 5(3):397 (2005); andMusyanovych, Anna; Adler, Hans-Jurgen Organic Chemistry IIIMacromolecular Society, 21(6):2209 (2005).

In some embodiments, the nanoshells can be formed via thiol groupfacilitated nanoparticle assembling. For example, biodegradablepoly(propylene sulfide) can be produced in nanoparticle form as shown byAnnemie Rehor (Ph.D. thesis, Swiss Federal Institute of Technology,Zurich, 2005). This polymer has thiol end-groups from thepolymerization, which can be maximized in number by exposing thenanoparticles to reducing conditions.

In some embodiments, the nanoshells can be modified to include atargeting molecule. The target molecule can be any peptides orantibodies such as ligands against receptors on an inflamed endothelium.Examples of such targeting molecules include, but are not limited to,antibodies to CD34, RGD, YIGSR, peptides and antibodies to IIbIIIa,heparin, hyaluronic acid, laminin, collagen, ICAM-1, ICAM-2, ICAM-3,fibrinogen, fibronectin, vitronectin, thrombospondin, osteopontin,integrins, VCAM-1, N-CAM, PECAM-1, IgCAM, folate, oligonucleotideaptamers, selectins, and cadherins.

Attachment of targeting molecule to nanoshells can be achieved byestablished methods. The targeting molecule can be attached to thenanoshell via covalent bonding or non-covalent conjugation. Non-covalentconjugation can be based on ionic interaction, hydrogen bonding or othertype of interaction. For example, after formation of the gold nanoshell,molecules functionalized with a thiol group can be used to modify thenanoshell surface for targeting of the nanoshell, or to stealth thenanoshell surface. Thiol-terminated molecules have been shown toself-assemble on gold surfaces. For example, thiol-terminatedpoly(ethylene glycol) (PEG) having a molecular weight of about 200Daltons to 10,000 Daltons, preferably between 500 Daltons to about 2,000Daltons can be used to stealth the nanoshell surface. The other end ofthe PEG chain can be functionalized with a targeting molecule such as apeptide or an antibody to target the nanoshell to specific tissue withinthe body.

In some embodiments, the targeting molecule can be attached to ananoshell via a spacer. A spacer molecule can be a short chain alkylgroup such as a C1-C20 alkyl, C3-C20 cycloalkyl, poly(ethylene glycol),poly(alkylene oxide). Some other spacer molecules can be, but are notlimited to, dextran, dextrose, heparin, poly(propylene sulfide),hyluronic acid, peptides, DNA, PVA and PVP.

Biocompatible Polymers

Polymers that can be used as the core substrate for forming thenanoshells described above can be biodegradable (either bioerodable orbioabsorbable or both) or nondegradable, and can be hydrophilic orhydrophobic.

Representative biocompatible polymers include, but are not limited to,poly(ester amide), polyhydroxyalkanoates (PHA),poly(3-hydroxyalkanoates) such as poly(3 -hydroxypropanoate),poly(3-hydroxybutyrate), poly(3-hydroxyvalerate),poly(3-hydroxyhexanoate), poly(3-hydroxyheptanoate) andpoly(3-hydroxyoctanoate), poly(4-hydroxyalkanaote) such aspoly(4-hydroxybutyrate), poly(4-hydroxyvalerate),poly(4-hydroxyhexanote), poly(4-hydroxyheptanoate),poly(4-hydroxyoctanoate) and copolymers including any of the3-hydroxyalkanoate or 4-hydroxyalkanoate monomers described herein orblends thereof, poly(D,L-lactide), poly(L-lactide), polyglycolide,poly(D,L-lactide-co-glycolide), poly(L-lactide-co-glycolide),polycaprolactone, poly(lactide-co-caprolactone),poly(glycolide-co-caprolactone), poly(dioxanone), poly(ortho esters),poly(anhydrides), poly(tyrosine carbonates) and derivatives thereof,poly(tyrosine ester) and derivatives thereof, poly(imino carbonates),poly(glycolic acid-co-trimethylene carbonate), polyphosphoester,polyphosphoester urethane, poly(amino acids), polycyanoacrylates,poly(trimethylene carbonate), poly(iminocarbonate), polyphosphazenes,silicones, polyesters, polyolefins, polyisobutylene andethylene-alphaolefin copolymers, acrylic polymers and copolymers, vinylhalide polymers and copolymers, such as polyvinyl chloride, polyvinylethers, such as polyvinyl methyl ether, polyvinylidene halides, such aspolyvinylidene chloride, polyacrylonitrile, polyvinyl ketones, polyvinylaromatics, such as polystyrene, polyvinyl esters, such as polyvinylacetate, copolymers of vinyl monomers with each other and olefins, suchas ethylene-methyl methacrylate copolymers, acrylonitrile-styrenecopolymers, ABS resins, and ethylene-vinyl acetate copolymers,polyamides, such as Nylon 66 and polycaprolactam, alkyd resins,polycarbonates, polyoxymethylenes, polyimides, polyethers, poly(glycerylsebacate), polypropylene fumarate), poly(n-butyl methacrylate),poly(sec-butyl methacrylate), poly(isobutyl methacrylate),poly(tert-butyl methacrylate), poly(n-propyl methacrylate),poly(isopropyl methacrylate), poly(ethyl methacrylate), poly(methylmethacrylate), epoxy resins, polyurethanes, rayon, rayon-triacetate,cellulose acetate, cellulose butyrate, cellulose acetate butyrate,cellophane, cellulose nitrate, cellulose propionate, cellulose ethers,carboxymethyl cellulose, polyethers such as poly(ethylene glycol) (PEG),copoly(ether-esters) (e.g. poly(ethylene oxide-co-lactic acid)(PEO/PLA)), polyalkylene oxides such as poly(ethylene oxide),poly(propylene oxide), poly(ether ester), polyalkylene oxalates,phosphoryl choline, choline, poly(aspirin), polymers and co-polymers ofhydroxyl bearing monomers such as 2-hydroxyethyl methacrylate (HEMA),hydroxypropyl methacrylate (HPMA), hydroxypropylmethacrylamide, PEGacrylate (PEGA), PEG methacrylate,2-methacryloyloxyethylphosphorylcholine (MPC) and n-vinyl pyrrolidone(VP), carboxylic acid bearing monomers such as methacrylic acid (MA),acrylic acid (AA), alkoxymethacrylate, alkoxyacrylate, and3-trimethylsilylpropyl methacrylate (TMSPMA),poly(styrene-isoprene-styrene)-PEG (SIS-PEG), polystyrene-PEG,polyisobutylene-PEG, polycaprolactone-PEG (PCL-PEG), PLA-PEG,poly(methyl methacrylate)-PEG (PMMA-PEG), polydimethylsiloxane-co-PEG(PDMS-PEG), poly(vinylidene fluoride)-PEG (PVDF-PEG), PLURONIC™surfactants (polypropylene oxide-co-polyethylene glycol),poly(tetramethylene glycol), hydroxy functional poly(vinyl pyrrolidone),biomolecules such as collagen, chitosan, alginate, fibrin, fibrinogen,cellulose, starch, dextran, dextrin, hyaluronic acid, fragments andderivatives of hyaluronic acid, heparin, fragments and derivatives ofheparin, glycosamino glycan (GAG), GAG derivatives, polysaccharide,elastin, or combinations thereof. In some embodiments, the nanoparticlescan exclude any one of the aforementioned polymers.

As used herein, the terms poly(D,L-lactide), poly(L-lactide),poly(D,L-lactide-co-glycolide), and poly(L-lactide-co-glycolide) can beused interchangeably with the terms poly(D,L-lactic acid), poly(L-lacticacid), poly(D,L-lactic acid-co-glycolic acid), or poly(L-lacticacid-co-glycolic acid), respectively.

Method of Use

The nano-constructs provided herein can be delivered or administered toa subject via any established mode of delivery. For example, thenano-constructs can be delivered by systemic delivery such as systemicinjection. In some embodiments, the nano-constructs can be administeredby local delivery such as direct injection. For disorders of thevascular system, the nano-constructs may be administered bycatheter-based devices. These would include single and dual needleinjection catheters, porous balloon catheters, balloon catheters withjets, and double balloon catheters.

Upon delivery to the target tissue, an energy source can be applied tothe nano-constructs. The nano-constructs can then absorb the energy andconvert it or translate it to heat so as to ablate the diseased tissue.The energy source can be in any form capable of reaching thenano-constructs and being absorbed and converted by the nano-constructsinto heat. In some embodiments, the energy source can be applied throughexternal radiation or through a catheter-based guidance system.

In some embodiments, the energy source is an electromagnetic radiationhaving a wave length ranging from 500 nm to 1500 nm. For example, theenergy source can be a near infrared radiation.

In some embodiments, the energy source is a fluctuating electromagneticfield. Such electromagnetic field can have a frequency ranging from1×10⁶ Hz to 6×10¹⁴ Hz. In some embodiments, the electromagnetic fieldcan have a frequency of 700 nm to 1300 nm where optical transmission isoptimal (Welch A.; van Gemert, M. e. Optical-Thermal Response of LaserIrradiated Tissue, Plenum Press: New York, 1995).

In some embodiments, the energy source can be applied to thenano-constructs by a catheter-based fiber-optic. The localization ofplaque can be imaged prior to the procedure or during the procedure byinterrogation with an attenuated radiation. For example, the plaque maybe imaged by optical coherence tomography using a wavelength of 1300 nm(Meissner O. A., et al. J Vasc Intery Radiol 2006; 17: 343-349) orintravascular ultrasound (Colombo et al., Circulation, 91:1676-88(1995)). This same wavelength could then be used to apply energy to thenano-constructs after they are administered.

The nano-construct described herein can be used to treat, prevent orameliorate a medical condition. Such a medical condition can be, e.g., atumor or nephropathic kidney. In some embodiments, such a site can be asite of atherosclerosis. Other medical conditions include, but are notlimited to, vulnerable plaque, diffuse atherosclerotic disease, diabeticretinopathy, aneurysm, anastomotic hyperplasia, claudication, chronictotal occlusion, dysfunctional endothelium, recurring thrombus, fibrinaccumulation, or combinations of these.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications can be made without departing from thisinvention in its broader aspects. Therefore, the appended claims are toencompass within their scope all such changes and modifications as fallwithin the true spirit and scope of this invention.

1. A method of treating or ameliorating a vascular condition,comprising: (a) administering to a subject nano-constructs capable ofabsorbing energy from an electromagnetic radiation or energy from afluctuating electromagnetic field and translating the energy into heat,(b) causing the nano-constructs to reach a target tissue, and (c)applying an energy to the nano-constructs to cause the nano-constructsto heat the target issue, wherein the nano-construct comprises ananoshell.
 2. The method of claim 1, wherein the causing comprisesallowing the nano-constructs to extravasate through leaky vasculature inthe target tissue.
 3. The method of claim 1, wherein the nano-constructscomprise targeting molecules on the surface of the nano-constructs. 4.The method of claim 3, wherein the targeting molecules aresurface-conjugated ligands against receptors on an inflamed endothelium.5. The method of claim 1, wherein the energy is a near infrared (MR)electromagnetic radiation applied through a catheter-based fiber-optic.6. The method of claim 1, wherein the energy is from electromagneticirradiation applied outside the body of the subject.
 7. The method ofclaim 2, wherein the nano-constructs comprise a surface-stealthingcompound on the surface of the nano-constructs such that the circulationtime of the nano-constructs is increased.
 8. The method of claim 7,wherein the surface-stealthing compound is poly(ethylene glycol).
 9. Themethod of claim 1, wherein the nanoshell comprises a material selectedfrom a metal, carbon, or a conducting polymer.
 10. The method of claim1, wherein the nanoshell comprises gold.
 11. The method of claim 1,wherein the nanoshell has a thickness in the range between about 2 nmand about 100 nm.
 12. The method of claim 1, wherein the vascularcondition is selected from atherosclerotic plaque, vulnerable plaque,diffuse atherosclerotic disease, diabetic retinopathy, aneurysm,anastomotic hyperplasia, claudication, chronic total occlusion,dysfunctional endothelium, recurring thrombus, fibrin accumulation, orcombinations of these.
 13. The method of claim 13, wherein theatherosclerotic plaque is located by imaging by interrogation with anattenuated radiation.
 14. The method of claim 1, wherein theadministering is achieved through a catheter. 15.-28. (canceled)